sd_ble_gap_rssi_get channel

[vn2000]

I want to get the RSSI of a connected device. The sequence will be as follows:

int8_t *p_rssi;

uint8_t *p_ch_index;

sd_ble_gap_rssi_start (m_conn_handle, BLE_GAP_RSSI_THRESHOLD_INVALID, 0x00);

sd_ble_gap_rssi_get(m_conn_handle, p_rssi, p_ch_index);

sd_ble_gap_rssi_stop (m_conn_handle);

The device is configured as a hid device connected to a smart phone.

Nordic Infocenter says p_ch_index is the pointer to the location where Channel Index for the RSSI measurement shall be stored.

I have only one connected phone. I wonder what the Channel Index has to do with this?

Besides, when I tried to get the rssi by implementing this function in a 2 second timer  I can no longer pair the device using the example ble_app_hid_mouse.

[Einar Thorsrud]

Hi,

I have only one connected phone. I wonder what the Channel Index has to do with this?

The channel index here lets you know which of the 40 BLE channels the measurement applies for. (BLE is always frequency hopping, using a number of channels, so this is not related to how many connections you have.)

Besides, when I tried to get the rssi by implementing this function in a 2 second timer  I can no longer pair the device using the example ble_app_hid_mouse.

I assume some error occurs since you observe this. Have you debugged to see what is going on? The easiest way to start is observe the logg. Then information about any detected errors will be printed in the log. UART logging is enabled by default in most examples, alternatively, you can enable RTT logging.

[vn2000]

I'm using SDK V15 and enabled UART logging.

I can see the following output to the hyperterminal that happened when I tried to pair:

<info> app: CONNECTED <error> app: Fatal error <warning> app: System reset

It looks like that doesn't give enough info. Please advise.

[vn2000]

I'm using Keil Compiler V5.28. I don't see where I can set it up a debug build.

Under the Debug drop down menu I don't see that option.

[Einar Thorsrud]

Hi,

Using Keil you need to edit the preprocessor symbols for your project (Project -> Options for target..., then C/C++ tab). Add "DEBUG" to the list of symbols. Rebuild and test again. (If you want to inspect the code with a debugger you should also disable optimization.)

[vn2000]

I added DEBUG at the end of Preprocessor Symbols Define, under C/C++.

After being compiled, I see even less debug info:

<info> app: CONNECTED

Nothing appeared after that. The device still failed to pair.

[Einar Thorsrud]

vn2000 said:

Nothing appeared after that. The device still failed to pair.

I understand. What we are trying to do now is to find out where the error is, not fix it (yet). If the example uses deferred logging, then the full log may not be written during an error. If so, you could try to get it by setting NRF_LOG_DEFERRED to 0 in sdk_config.h and removing the call to NRF_LOG_PROCESS() in your application. Alternatively, you can place a breakpoint and inspect the error_info_t struct in app_error_fault_handler using a debugger to see the error there (filename, line number, and error code).

[vn2000]

I think I found the issue. I need to wait for some time after the device is connected before I can measure the RSSI. I have some other issues but let's close this issue for now.

Thanks.